Many factors result in car accidents, and sometimes multiple causes contribute to a single accident. Factors include the following:

• Driver distraction, including fiddling with technical devices as noted previously, talking with passengers, eating or grooming in the car, dealing with children or pets in the back seat, or attempting to retrieve dropped items.
  

• Driver impairment by tiredness, illness, alcohol or other drugs, both legal and illegal. MADD (Mothers Against Drunk Driving) is an organization made up of the families of the dead who were killed in car accidents caused by drunk drivers.
  

• Mechanical failure, including flat tires or tires blowing out, brake failure, axle failure, steering mechanism failure.
  

• Road conditions, including foreign obstacles or substances on the road surface; rain, ice, or snow making the roads slick; road damage including pot holes.
  

• Speed exceeding safe conditions, such as the speed for which the road was designed, the road condition, the weather, the speed of surrounding motorists, and so on.
  

• Road design and layout. Some roads are notorious for being accident "black spots" for a whole variety of reasons, many subtle and not necessarily immediately obvious. These include alignment, visibility, camber and surface conditions, road markings, etc. Finding out the causes for a repeated series of accidents on the same stretch of road is becoming a science in itself.
  

Legal consequences

Car accidents often carry legal consequences in proportion to the severity of the accident. Nearly all common law jurisdictions impose some kind of requirement that parties involved in a collision (even with only stationary property) must stop at the scene, and exchange insurance or identification information or summon the police. Failing to obey this requirement is the crime of hit and run. Most car accidents can be settled without using an attorney.

Parties involved in an accident may face criminal liability, civil liability, or both. Usually, the state starts a prosecution only if someone is severely injured or killed, or if one of the drivers involved was clearly intoxicated or otherwise impaired at the time the accident occurred. Charges might include driving under the influence of alcohol, assault with a deadly weapon, manslaughter, or murder; penalties range from fines to jail time to prison time to death.

As for civil liability, automobile accident personal injury lawsuits have become the most common type of tort. Because these cases have been litigated often in the developed First World nations, the legal questions usually have been answered in prior judgments. So, the courts most usually decide solely the factual questions of who is at fault, and how much they (or their insurer) must pay out in damages to the injured plaintiff.